97L growing more organized, will bring heavy rain to the Lesser Antilles

By: Dr. Jeff Masters , 03:55 PM GMT am 19. Juli 2009

Share this Blog
1
+

The tropical wave near 12N 52W, about 600 miles east of the Lesser Antilles Islands (97 L), has grown more organized this morning as it tracks west at about 20 mph. This wave is surrounded by an area of very dry air from the Sahara Desert, but 97L has been able to steadily moisten a large region of the atmosphere over the past day, insulating itself from the dry air. This moistening process has been aided by sea surface temperatures (SSTs) that have steadily increased from 26.5°C to 27.5°C, plus the presence of only 10 knots of wind shear. The system now has a small area of intense thunderstorms near its center, with some rotation of the cloud pattern evident at mid-levels of the atmosphere. An upper-level outflow channel has opened to the north, and there is evidence that surface spiral bands are beginning to form. This morning's QuikSCAT pass missed 97L, so we don't know what is happening at the surface.

Wind shear is a modest 10 knots over the disturbance, and is forecast to remain in the moderate 10 - 15 knot range through Monday morning. This should allow further development to occur today, and 97L could be approaching tropical depression strength on Monday as it moves through the central Lesser Antilles Islands. Monday night, shear is expected to rise to 20 - 30 knots, thanks to the presence of a trough of low pressure at upper levels of the atmosphere over the eastern Caribbean. Since 97L is a relatively small system, it is very vulnerable to wind shear. This shear may be able to drive some of the dry air west of 97L deep into its interior, significantly disrupting the disturbance. Shear will remain high along 97L's path through Thursday, when the storm should be in the western Caribbean near Cuba. If there is anything left of 97L by then, some development is possible. The National Hurricane Center gave 97L a low (less than 30% chance) of developing into a tropical depression in the next 48 hours in their 8am Tropical Weather Outlook. However, I'd say the odds are now in the medium range (30 - 50%).

None of the computer models are forecasting tropical storm development over the next seven days.


Figure 1. Current satellite image of African wave 97L.

I'll have an update Monday morning. As 97L approaches the islands, you may want to follow local observations there using our wundermap for 97L.

Jeff Masters

Reader Comments

Comments will take a few seconds to appear.

Post Your Comments

Please sign in to post comments.

or Join

Not only will you be able to leave comments on this blog, but you'll also have the ability to upload and share your photos in our Wunder Photos section.

Display: 0, 50, 100, 200 Sort: Newest First - Order Posted

Viewing: 1065 - 1015

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45 | 46 | 47 | 48Blog Index

1065. beell
Quoting homelesswanderer:


UMMM? Sorry that one went over my head? Just tried to lighten things up. I'll go back to my lurk.


Talkin about the tree roots coming up above the ground level cause the soil around here has been subsiding-sorry.
Member Since: Posts: Comments:
I'd wait for the 00Z GFS to really start declaring lower shear in its path.
Member Since: Posts: Comments:
Quoting futuremet:
lol I just experience a very strong thunderstorms. Winds were sustained at 35mph with frequent gusts near 45, and we also had some hail too.


There was a Wind Gust to 70MPH at the Fort Pierce Airport.
Member Since: Posts: Comments:
Ecmwf has been more accurate this year than gfs.I am not saying gfs is a bad model,its just not having its year.
Member Since: Posts: Comments:
Quoting beell:


Afternoon, homeless. Just added 2,000 lbs of topsoil to my front weedbed. Was not my idea.


UMMM? Sorry that one went over my head? Just tried to lighten things up. I'll go back to my lurk.
Member Since: Posts: Comments:
Quoting STORMMASTERG:
The gfs has been wrong all year,its been forcasting ghost storms/wrong cape/wrong shear.I can't possibly trust this.Based on trends 5 to 15kt shear will stay next 3 to 4 days.I am going with this forcast for 97l.


I find the GFS the most reliable when it comes to forecasting shear, albeit it has its weaknesses.
Member Since: Juli 19, 2008 Posts: 43 Comments: 4051
The gfs has been wrong all year,its been forcasting ghost storms/wrong cape/wrong shear.I can't possibly trust this.Based on trends 5 to 15kt shear will stay next 3 to 4 days.I am going with this forcast for 97l.
Member Since: Posts: Comments:
well if the NHC is basing their predicitions on impending shear, like was shown the GFS is showing more favorable shear then they did before

meaning the NHC may reconsider their thinking, we will see.
1057. CUBWF
With wind sheer remaining low it has better chance to become TD diuring dmax
Member Since: Posts: Comments:
Quoting DeerfieldBeachGuy:
outflow boundary causing some pretty nasty weather here in Deerfield Beach; winds are gusting up to 50 mph with some isolated gusts that feel even higher.

Not too much in the way of rain yet here but its coming.

All the high-def radars are down in S Fla..
Member Since: Posts: Comments:
Quoting extreme236:
Holding up decently considering its right at DMIN there.

Sure is Dmin
Member Since: Mai 16, 2009 Posts: 1 Comments: 1231
Quoting Funkadelic:


Very symetrical looking system in that photo.. D-MAX will produce Anna possibly?

I dont think Ana...Maybe an orange, or dare I say red circle later on tonight to 8am tomorrow.
Member Since: Posts: Comments:
outflow boundary causing some pretty nasty weather here in Deerfield Beach; winds are gusting up to 50 mph with some isolated gusts that feel even higher.

Not too much in the way of rain yet here but its coming.
Member Since: Posts: Comments:
Holding up decently considering its right at DMIN there.
Member Since: Posts: Comments:
1050. beell
Quoting STORMMASTERG:
The gfs has been overdoing everything this year.On days it shows cape in the us at 4,000 its 2,000.Its been hyping all year.Don't buy its solution.Max 15kt shear for next 4 days.


Who uses the GFS for CAPE over the CONUS?
Member Since: Posts: Comments:
GFS shear forecast is interesting to say the least.
Member Since: Posts: Comments:
Quoting FloridaTigers:
As a half Cuban, no one ever uses the suffix "-cito" after every damn word. Its sort of silly.

Meanwhile in the tropics. In my non-professional opinion, I could see shear remaining relatively low enough for atleast TD development in the next 48 hours.

It's degrading...He called Adrian "Adriancito"...little Adrian...
Member Since: Posts: Comments:
Btw... comment 1041 is totally kidding. It kinda has to have CDO for an eye to pop, and the coldest cloud tops are to the NE.
Member Since: Posts: Comments:
1045. Sockets
Hey all, 97l looking mighty impressive considering the approach of D-Min...W456 it appears the GFS shear forecast is becoming more conducive for development...really depends on the track of 97l...appears to still be moving slightly south of due west.
Member Since: Posts: Comments:
It looks like 97L will pass directly over my house tomorrow....
Quoting Stormchaser2007:
Great now were gonna have people running around saying it has an eye.



"I think I see an eye! I think it is a pinhole eye!"
Member Since: Posts: Comments:
Quoting Stormchaser2007:
Great now were gonna have people running around saying it has an eye.


OMG OMG OMG! It has a pinhole eye!!!!
Member Since: Posts: Comments:
Link shear is forcast to be 5kt until tomorrow morning.Shear continues to weaken in the caribean too.
Member Since: Posts: Comments:
1039. Patrap
RBG




Floater 1 - RGB Color Infrared Loop
Member Since: Juli 3, 2005 Posts: 426 Comments: 128878
Quoting SavannahStorm:
Asse'avec l'Espagnol, y a-t-il des francophones dehors là ?


Not sure how many people speak French on here fluently.
Member Since: Posts: Comments:
Great now were gonna have people running around saying it has an eye.

Member Since: Posts: Comments:
As a half Cuban, no one ever uses the suffix "-cito" after every damn word. Its sort of silly.

Meanwhile in the tropics. In my non-professional opinion, I could see shear remaining relatively low enough for atleast TD development in the next 48 hours.
Member Since: Mai 17, 2009 Posts: 0 Comments: 559
Quoting BaltOCane:


It is nice for blog to be bilingual, though, lol!


Oh, without a doubt. hehe.
Member Since: Posts: Comments:
Asse'avec l'Espagnol, y a-t-il des francophones dehors là ?
Member Since: Posts: Comments:
Quoting KYhomeboy:
Ummm... guys...quite a few of us on here are bilingual or at least fluent in spanish so yapping away thinking other people can't understand isn't too smart. Especially if you use a bunch of cognates. lol. Who cares who is more cubano than who anyway. Back to the WEATHER since this is a weather blog and not a place to post scripts for a telenovela


Exactly. I think a few children need to go to time out.
Member Since: Posts: Comments:
1032. Patrap
AVN Image,Latest AL97



Floater 1 AVN Color Imagery Loop
Member Since: Juli 3, 2005 Posts: 426 Comments: 128878
Getting some marble hail now with very heavy rains. Pretty cool.
Member Since: Posts: Comments:
Quoting jeffs713:
I think the blog just reached a new low. People are now trading insults in another language. Impressive.


It is nice for blog to be bilingual, though, lol!
Member Since: Posts: Comments:
The gfs has been overdoing everything this year.On days it shows cape in the us at 4,000 its 2,000.Its been hyping all year.Don't buy its solution.Max 15kt shear for next 4 days.
Member Since: Posts: Comments:
System is Ana, 40mph winds... it's too defined not to be classified.
Member Since: Posts: Comments:
Quoting jeffs713:
I think the blog just reached a new low. People are now trading insults in another language. Impressive.


Doesnt surprise me one bit..lol
Member Since: Posts: Comments:
lol I just experience a very strong thunderstorms. Winds were sustained at 35mph with frequent gusts near 45, and we also had some hail too.
Member Since: Juli 19, 2008 Posts: 43 Comments: 4051
1023. JLPR
Quoting BurnedAfterPosting:
yo WS nice going, I got one for you

Est%uFFFDs a punto de sustituir%uFFFD por el espacio vac%uFFFDo

Translation

You are about to be replaced with empty space


actually it would be :
estas a punto de ser sustituido por espacio vacio
=P

and actually he referred to one person when he said americanito ignorante no dijo americanos ignorantes which would have been a plural =]
now enough with grammar
... how ever we are all Americans... I dont understand why people say american when they refer to north Americans?

I see 97L is loosing convection fast... DMIN hitting it hard?
Member Since: Posts: Comments:
I know we been focusing alot on 97L, but look for a surface trough to form offshore the US East coast by Wednesday with most models showing development by Friday.
Member Since: Posts: Comments:
Quoting 789:
vote d rip


98.
Member Since: Posts: Comments:
I think the blog just reached a new low. People are now firing off insults in another language. Impressive.
Member Since: Posts: Comments:
Quoting KrazyKaneLove:
Hi everyone, first time posting this season, this is reminding me of 2007 a bit


Hm I recognize you from last year. Good to see a familiar face.
Member Since: Posts: Comments:
yeah, it did look like the shear was going to be pretty favorable... lessening even...
Member Since: Posts: Comments:
Quoting Stormchaser2007:


Its getting pretty nasty here...very heavy rain with a gust so far near 50mph.


Yea,

The Special WX Statement said to expect 50 Mph Wind's. But the 70 Mph Gust triggered a warning.
Member Since: Posts: Comments:
1016. 789
vote d rip
Member Since: Posts: Comments:
Quoting Weather456:
GFS Shear

12 hrs



24 hrs



48 hrs




Whoa...Large change. Interesting since the GFS is what the NHC uses for a shear forecast. Looks pretty favorable. We'll see though.
Member Since: Posts: Comments:

Viewing: 1065 - 1015

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45 | 46 | 47 | 48Blog Index

Top of Page

About

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

Local Weather

Scattered Clouds
61 °F
Teils Wolkig